David, Damper felt needs to be replaced if is old and hard, torn or has string marks so deep they impede dampening. Dampers work because; Felt is new and resiliant and will suppress vibration Dmpers are fitted and regulated well Weight suppress vibration Springs work to suppress vibration. Hard and stiff felt will not work well and will create noise when coming in comtact with the moving strings. New and resiliant felt works because of its resiliance. Properly fitted and regulated dampers work because; Front and back pieces touch at exactly the same time Left and right parts touch their respective stings at the same time The wire moves straight up and down, freely The weight and springs match the energy level of the string(s) These conditions are often not easy to attain, but using felt fluffers like the ones sold by Ruth Jordon can help with older felts, a nice pair of felt squeezers like Schaff sell, providing the jaws are paralell, touch when closed, are polished and shortened. These allow you to massage bichords so they come down and touch both strings and on trichords you can ease one side for felt or strings that are uneven. When installing dampers work with one at a time, get it perfect then go on to the next one. Doing this, one at a time, when the job is finished there is likely very little to do to finish the job. I hope I have commented to your inquiry, if not please let me know. Newton nhunt@rci.rutgers.eduH
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